JSFiddle - React, Tailwind, and code Playground

HTML

<form name="morning">
    <input type="checkbox" name="class[]" value="name 1" />
    <input type="checkbox" name="class[]" value="name 2"/>
    <input type="checkbox" name="class[]" value="name 3"/>
</form>

JavaScript

function checkboxlimit(el, limit) {
    alert(el[0].value);
}

document.onload = checkboxlimit(document.forms.morning["class[]"], 2);